ppc: Add ByteReverse Function

Change-Id: I91ed4bf22231c6080b2c5e445ea407d076baeadc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3175374Reviewed-by: Milad Fa <mfarazma@redhat.com>
Commit-Queue: Junliang Yan <junyan@redhat.com>
Cr-Commit-Position: refs/heads/main@{#76994}

src/codegen/ppc/macro-assembler-ppc.cc

@@ -3516,6 +3516,27 @@ void TurboAssembler::SwapSimd128(MemOperand src, MemOperand dst,
   addi(sp, sp, Operand(2 * kSimd128Size));
 }
 
+void TurboAssembler::ByteReverseU16(Register dst, Register val) {
+  subi(sp, sp, Operand(kSystemPointerSize));
+  sth(val, MemOperand(sp));
+  lhbrx(dst, MemOperand(r0, sp));
+  addi(sp, sp, Operand(kSystemPointerSize));
+}
+
+void TurboAssembler::ByteReverseU32(Register dst, Register val) {
+  subi(sp, sp, Operand(kSystemPointerSize));
+  stw(val, MemOperand(sp));
+  lwbrx(dst, MemOperand(r0, sp));
+  addi(sp, sp, Operand(kSystemPointerSize));
+}
+
+void TurboAssembler::ByteReverseU64(Register dst, Register val) {
+  subi(sp, sp, Operand(kSystemPointerSize));
+  std(val, MemOperand(sp));
+  ldbrx(dst, MemOperand(r0, sp));
+  addi(sp, sp, Operand(kSystemPointerSize));
+}
+
 void TurboAssembler::JumpIfEqual(Register x, int32_t y, Label* dest) {
   CmpS64(x, Operand(y), r0);
   beq(dest);

src/codegen/ppc/macro-assembler-ppc.h

@@ -408,7 +408,7 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
 
   template <class _type, class bin_op>
   void AtomicOps(MemOperand dst, Register value, Register output,
-                 Register scratch, bin_op op) {
+                 Register result, bin_op op) {
     Label binop;
     lwsync();
     bind(&binop);
@@ -428,19 +428,19 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
       default:
         UNREACHABLE();
     }
-    op(scratch, output, value);
+    op(result, output, value);
     switch (sizeof(_type)) {
       case 1:
-        stbcx(scratch, dst);
+        stbcx(result, dst);
         break;
       case 2:
-        sthcx(scratch, dst);
+        sthcx(result, dst);
         break;
       case 4:
-        stwcx(scratch, dst);
+        stwcx(result, dst);
         break;
       case 8:
-        stdcx(scratch, dst);
+        stdcx(result, dst);
         break;
       default:
         UNREACHABLE();
@@ -599,6 +599,10 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
                    Simd128Register scratch);
   void SwapSimd128(MemOperand src, MemOperand dst, Simd128Register scratch);
 
+  void ByteReverseU16(Register dst, Register val);
+  void ByteReverseU32(Register dst, Register val);
+  void ByteReverseU64(Register dst, Register val);
+
   // Before calling a C-function from generated code, align arguments on stack.
   // After aligning the frame, non-register arguments must be stored in
   // sp[0], sp[4], etc., not pushed. The argument count assumes all arguments